Increasing efforts have in recent years been made by manufacturers and governmental regulation to prevent or minimize injuries sustained by automobile passengers during accidental collisions. For instance, a series of inventions provides seat constructions that serve to minimize or prevent whiplash and similar injuries that occur upon rear end impact at a vehicle in which the passenger is riding such as those inventions provided in U.S. Pat. Nos. 5,181,763, 5,290,091, and 5,580,524, the disclosures of which are incorporated herein by reference.
Many variables can influence the forces to the spine that can cause injury, for instance, the size of the vehicles, the size of the occupants, and the speeds of the vehicles. Attempting to prevent whiplash injury thus can be a daunting task. However, reducing the global movement of the entire spine and the relative movement of each vertebra appear to be the most practical approach in the prevention of injury to the spine. To accomplish this, all spinal curves should be supported and decelerated at as close to a zero delta velocity as possible. This requires support systems within head-neck restraints and seats that are contoured to the spine to reduce the spinal straightening observed during rear end impact. Additionally, the head-neck restraint and seat back should have complementary dampening characteristics so that simultaneous deceleration of the head, neck, thoracic, and lumbopelvic areas can be achieved.
Dellanno, U.S. Pat. Nos. 5,181,763 and 5,290,091 provide an apparatus for preventing whiplash-related injuries to a passenger in a vehicle. The characteristic shapes of the devices shown therein define a supporting means and contour located behind the cranium and cervical spine of the passenger that interfit with the posterior contour of the passenger's cranium and cervical spine. The supporting means interacts with the passenger during rear end impact to maintain the pre-collision shape of the supported spinal curves, to thereby aid in the avoidance of whiplash and similar injuries. The support contour basically presents a first surface located behind the seated passenger's cranium for contacting the approximate center of mass of the cranium and supporting the approximate central posterior area of the seated passenger's cranium, and a second surface located below the first surface and defining a substantially convex smooth curve, a maximum protrusion point of which in the direction of passenger support projects anteriorly relative to where the first surface contacts the center of mass of the related passenger's cranium, said second surface thereby contacting and supporting the posterior portion of the seated passenger's cervical spine substantially simultaneously with the contact of the seated passenger's cranium with said first surface.
Dellanno, U.S. Pat. No. 5,580,124 provides a vehicle-installed supporting seat for a passenger, which includes a seat back provided with an integral head-neck restraint comprising a cranium support portion and a cervical spine support portion. Each said portion includes a layer of resilient material supported on an underlying inflexible support shell, which together act to effectively define a contour that interfits with the posterior contour of the passenger's cranium and cervical spine. The support shell is rearwardly displaceable upon being subjected to impressed forces generated from the passenger pressing against the restraint as a result of a rear end impact at said vehicle. A controllably deformable energy absorbing crush zone is disposed to the rear of the shell as to be compressed by the rearward displacement of the shell. The interfitting contour and thereby the inflexible shell, upon being displaced by said forces toward the underlying crush zone, retain the shape of the contour, whereby the cervical and cranium support portions act to substantially simultaneously decelerate the cranium and cervical spine of the passenger during a vehicle rear end impact, while the controlled deformation of the crush zone absorbs energy, to prevent whiplash-related injuries to the passenger.
The apparatus of Dellanno, U.S. Pat. No. 5,580,124 preferably further includes a thoracic and lumbar spine support portion which are defined by downward extension of the support shell, resilient material and contour; whereby the thoracic and lumbar spine portion of the passenger are decelerated with the cranium and cervical spine during a rear end impact.
The thoracic section of the human spine is believed to be compressed and flattened during a rear end impact. In addition to being injured, this flattening of the thoracic spine causes axial loading into the cervical spine as the weight of the head and upward pressure of the flattening thoracic spine serve as end point forces to damage the cervical spine. Where present, the thoracic portion of the above seat serves to prevent the flattening of the thoracic spine by having a kyphotic or concave firm contoured shell that takes the shape of the human thoracic spine and maintains this shape during rear end impact. This firm contoured shell precedes the crush zone material which plastically deforms and produces a controlled damping of the forces incurred during a rear end collision.
The lumbar section of the seat will conform to the lumbar spinal curves of the human anatomy. The initial foam that contacts the occupants is combined with the crush zone feature to maximize the energy-absorbing feature of this technology.
It is essential that upon a rear impact at the vehicle, a relatively inflexible surface which approximately conforms to the spine of the seated passenger (herein referred to as the “shaped surface”) provides a restraining boundary which maintains the normal curvature of the spine; this despite the fact that the passenger will be subjected to large forces generated by the impact which would otherwise rearwardly accelerate the passenger with respect to the vehicle as a frame of reference.
Dellanno, U.S. Pat. No. 7,090,292 provides an apparatus for preventing or limiting spinal injuries to a passenger seated in a forward facing position in a moving vehicle during vehicular impact or sudden deceleration. The apparatus includes a vehicle-installed supporting seat for the passenger, the seat having a support portion behind the seated passenger which includes a resilient surface in contact with the supported passenger. The resilient portion is supported on an underlying stiff support shell. A controllably deformable energy absorbing crush zone is disposed to the rear of the shell as to be compressed by rearward displacement of the passenger, whereby the support portion acts to decelerate the supported spine of the passenger during a vehicle rear end impact, while the controlled deformation of the crush zone absorbs energy, to prevent or limit spinal injuries to the passenger. The crush zone material is characterized in a rear end collision by exhibiting a total energy absorption of the kinetic energy gained by the impact accelerated passenger of at least 80%; and the coefficient of restitution for the crush zone material being in the range of 0.05 to 0.4.
Dellanno, U.S. Pat. No. 8,016,350 provides a vehicle seat for use in military vehicles that provides increased protection for a combatant soldier. The seat includes a seat portion having a layer of high impact energy absorbing material. A back support portion adjoined to the rear of the seat portion extends upwardly for supporting the rearward side of the seated soldier. The back portion has a lower section for supporting the thorax and lower back, and two overlying sections which are positionable for supporting and restraining rearward movement of the helmeted or unhelmeted head and the neck. The overlying sections are moveable toward and away from the soldier and together define a surface and contour which interacts with the seated soldier during rear end impact to maintain the pre-collision shape of the soldier's supported spinal curves, to aid in avoidance of whiplash and similar injuries. Swivelable side portions actuated by sensors flank the sides of the soldier for further protection.
It is necessary for some seats to protect occupants from impact. In the airline industry, for example, regulations call for a seat that can protect a passenger from a specified shock input. Traditionally, a thick foam cushion on the seat pan would be used to absorb the shock. Theoretically, the additional sway space would be enough to absorb the shock. Testing has proved this to be inadequate, however. In fact, the cushion can actually cause amplification of the shock input. Bottoming out or compression of the foam to a maximum may result in rebound of the foam, which can amplify a shock. Other problems facing seating designers include designing a seat for a wide range of occupant sizes and shapes. These all must be achieved while meeting the economic criteria of cost and weight.
It is desirable to transfer vertical underbody blast loading from underneath a vehicle through the seat and into the sacral region of the spine and divert most of the loading to the sacral-iliac joint. This results in spreading the force over a greater surface area and diverting more energy to the iliac bones, which is a much easier injury to correct than a spinal fracture which can result in paralysis.